Printed on: Thu Feb 09 2023, 12:00:11 AM(EST) Status: Currently Official on 09-Feb-2023 DocId: GUID-9B140FFF-9FC8-45B3-9BB6-CA5BA6E1EE5A_6_en-US

Printed by: Dang Van Vu Official Date: Official as of 01-Dec-2022 Document Type: NF @2023 USPC
Do Not Distribute DOI Ref: a9hsp DOI: https://doi.org/10.31003/USPNF_M724_06_01
1

CS = concentration of USP Adipic Acid RS in the

Adipic Acid Standard solution (mg/mL)
CU = concentration of Adipic Acid in the Sample
solution (mg/mL)

Acceptance criteria: 98.0%–102.0% on the dried basis

IMPURITIES
• RESIDUE ON IGNITION á281ñ: NMT 0.1%
• LIMIT OF NITRATES
Standard stock solution: 1.63 mg/mL of potassium nitrate
C6H10O4 146.14
Standard solution: Dilute 1 mL of the Standard stock
Hexanedioic acid; solution with water to 10 mL. Dilute 1 mL of this solution
1,4-Butanedicarboxylic acid CAS RN®: 124-04-9. with water to 50 mL to obtain a solution containing 2
DEFINITION µg/mL of nitrate.
Adipic Acid contains NLT 98.0% and NMT 102.0% of adipic Sample solution: Transfer 5 g of Adipic Acid to a 50-mL
acid (C6H10O4), calculated on the dried basis. volumetric flask. Dissolve in water, with heating, and dilute
with water to volume. Allow to cool and crystallize and then
IDENTIFICATION pass through a sintered-glass filter. Wash the filter with
• A. SPECTROSCOPIC IDENTIFICATION TESTS á197ñ, Infrared water, and collect the filtrate and washings until a volume
Spectroscopy: 197K of 50 mL is obtained. [NOTE—This solution is also to be
• B. The retention time of the adipic acid peak of the used for Chloride, Sulfate, and Iron.]
Sample solution corresponds to that of the Standard Control: 2 mg/L of potassium permanganate

al
solution, as obtained in the Assay. Analysis: Transfer 1.0 mL of the Sample solution, 1.5 mL of
ASSAY the Standard solution, and 1 mL of water (blank) to three
• PROCEDURE separate flasks. To each flask add 2 mL of ammonium
Solution A: 6.8 mL of 85% phosphoric acid in 4000 mL of hydroxide, 0.5 mL of 10 mg/mL manganese sulfate, and
water
ci 1 mL of 10 mg/mL sulfanilamide, and dilute each solution
Solution B: Acetonitrile with water to 20 mL. Add 100 mg of zinc powder to each
of the three flasks, and cool in an ice bath for 30 min,
Mobile phase: See Table 1.
shaking the solutions periodically. Separately filter 10 mL of
Table 1
each solution, cool in an ice bath, and then add 2.5 mL of
hydrochloric acid and 1 mL of 10 mg/mL of
Time Solution A Solution B naphthylethylenediamine dihydrochloride. Allow the
ffi
(min) (%) (%)
solutions to stand at room temperature for 15 min.
0.0 97 3 System suitability: The test is invalid if the concomitantly
5.0 97 3
prepared blank solution is darker than the Control.
Acceptance criteria: The color of the solution containing
20.0 45 55 the Sample solution is not darker than the concomitantly
O

20.1 97 3
prepared solution containing the Standard solution (NMT
30 ppm).
• CHLORIDE AND SULFATE á221ñ, Chloride
Re-equilibrate the column at the initial Mobile phase Sample: A 5-mL portion of the Sample solution from Limit of
composition before the next injection. Nitrates
Diluent: Acetonitrile and Solution A (3:97) Analysis: Proceed as directed in the chapter.
Standard solution: 0.5 mg/mL of USP Adipic Acid RS in Acceptance criteria: The Sample shows no more chloride
Diluent than a corresponding 0.14-mL portion of 0.020 N
Sample solution: 0.5 mg/mL of Adipic Acid in Diluent hydrochloric acid (NMT 0.02%).
Chromatographic system • CHLORIDE AND SULFATE á221ñ, Sulfate
(See Chromatography á621ñ, System Suitability.) Sample: A 5-mL portion of the Sample solution from Limit of
Mode: LC Nitrates
Detector: UV 209 nm Analysis: Proceed as directed in the chapter.
Column: 4.6-mm × 15-cm; 3-µm packing L1 Acceptance criteria: The Sample shows no more sulfate
Column temperature: 40° than a corresponding 0.26-mL portion of 0.020 N sulfuric
Flow rate: 1.0 mL/min acid (NMT 0.05%).
Injection volume: 30 µL • IRON á241ñ
System suitability Sample: A 10-mL portion of the Sample solution from Limit
Sample: Standard solution of Nitrates
Suitability requirements Analysis: Proceed as directed in the chapter.
Tailing factor: NMT 2.0 Acceptance criteria: NMT 10 ppm
Relative standard deviation: NMT 0.7%
Analysis Change to read:
Samples: Standard solution and Sample solution
Calculate the percentage of adipic acid (C6H10O4) in the • RELATED SUBSTANCES
portion of Adipic Acid taken: Solution A, Solution B, Mobile phase, Diluent, and
Chromatographic system: Proceed as directed in the
Result = (rU/rS) × (CS/CU) × 100 Assay.
Standard solution: 5 µg/mL of USP Adipic Acid RS
rU = peak area of adipic acid from the Sample solution Sample solution: 5 mg/mL of Adipic Acid in Diluent
rS = peak area of adipic acid from the Standard solution

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Printed on: Thu Feb 09 2023, 12:00:11 AM(EST) Status: Currently Official on 09-Feb-2023 DocId: GUID-9B140FFF-9FC8-45B3-9BB6-CA5BA6E1EE5A_6_en-US
Printed by: Dang Van Vu Official Date: Official as of 01-Dec-2022 Document Type: NF @2023 USPC
Do Not Distribute DOI Ref: a9hsp DOI: https://doi.org/10.31003/USPNF_M724_06_01
2

System suitability Result = (rU/rS) × (CS/CU) × (1/FR) × FC × 100

Sample: Standard solution
[NOTE—See Table 2 for the relative retention times.] rU = peak area of each individual impurity from the
Sample solution
Table 2 rS = peak area of adipic acid from the Standard solution
Relative Relative CS = concentration of USP Adipic Acid RS in the
Retention Response Standard solution (µg/mL)
Compound Name Time Factor CU = concentration of Adipic Acid in the Sample
Maleic acid 0.31 140 solution (mg/mL)
FR = relative response factor from Table 2 for known
Succinic acid 0.35 0.88 impurities (use FR = 1 for unknown impurities)
Fumaric acid 0.39 179 FC = conversion factor, 0.001 mg/µg (µg to mg)
Glutaric acid 0.59 0.94
Acceptance criteria
Adipic acid 1.00 1.00 Individual impurity: NMT 0.1%
Total impurities: NMT 0.5%
Pimelic acid 1.21 0.91

Valeric acid ▲
1.46 0.88▲ (ERR 1-Dec-2022)
SPECIFIC TESTS
• MELTING RANGE OR TEMPERATURE á741ñ: 151°–154°
Hexanoic acid 1.77 0.59 • LOSS ON DRYING á731ñ: Dry a sample at 105° for 3 h; it loses
NMT 0.2% of its weight.
Suitability requirements ADDITIONAL REQUIREMENTS
Tailing factor: NMT 2.0

al
• PACKAGING AND STORAGE: Preserve in a tight container. No
Relative standard deviation: NMT 5.0% storage requirements are specified.
Analysis • USP REFERENCE STANDARDS á11ñ
Samples: Standard solution and Sample solution USP Adipic Acid RS
Calculate the percentage of each individual impurity,
excluding any solvent peaks, in the portion of Adipic Acid
taken:
ci
ffi
O

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